The purity however varies depending on the refining agent used. The purity of the gold is then tested in the lab. The most commonly used element is Carbon. During the cupellation method impure silver is mixed with Nitric acid and then subjected to high temperatures in a cupellation heating system. This is usually done to liquid gold. Copper is usually refined through an electrolytic process. The precious metals include Silver, platinum and Gold. Metal refinery for Iron involves removal of Oxygen from the ore. Gold refinery is done after smelting so as to separate pure gold from other metals. Precious metal refinery is very common especially with the increased use of precious metals in production of various valuable commodities. Lead is purified by subjecting it to high temperatures. Usually pure gold will show a percentage purity of 99. Silver and gold impurities are removed by adding Zinc. The impurities are then separated and pure Lead is cooled. Silver refinery can be done using three methods which include cupellation, amalgamation and electric refining. The form of Iron formed is called wrought Iron. Once they dissolve the mixture floats at the top leaving pure Lead. Metal refinery involves the removal of impurities from a metal. Once the gold smelters are through, they pass the impure gold on for refining. The temperature should be higher than its melting point. The most common impurity found in gold is silver. The Lead ore is usually an Oxide of Iron. Chemical processes may be involved in metal refinery, but they do not alter the chemical composition of the end product. Its then crushed and distilled. Metal refinery takes different forms depending on the type of metal. To purify it further, limestone is added to wrought Iron and the mixture is heated at higher temperatures. Among mostly purified metals include Lead, Copper, Iron and precious metals. Zinc is used since silver and gold dissolve faster and easily in Zinc compared to Lead. Limestone contains Calcium which bonds with Silicates in the Iron forming a mixture which floats leaving pure Iron also known as pig Iron. During electric refining, electric waves are passed through the impure Silver over some period of time until a pure form of Silver is obtained. All these methods can be used to separate silver from gold.9. Amalgamation involves mixing the ore with salt and liquid Mercury. Once a current is passed, copper from the anode dissolves in the electrolyte and is then deposited at the cathode. Unlike electric motorcycle china manufacturer other processing methods, refinery does not cause any chemical changes to the end product. During gold refinery process, borax and soda ash are added to the impure gold to remove impurities.Ca, AZ (prHWY. Carbon binds with Oxygen to form Carbon Dioxide gas which escapes to the atmosphere. This involves creating a cell using impure copper as the anode, pure copper as the cathode and Copper Sulphate as the electrolyte. Sodium Carbonate can be added prior to heating so as to avoid the release of poisonous gases. To remove the Oxygen, heat and other chemical elements are usually used.